Newer Form of Heparin Better at Preventing Clots After Stroke

Enoxaparin cut the risk by additional 43 percent, study found

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THURSDAY, April 19, 2007 (HealthDay News) -- A newly engineered form of the blood-thinning drug heparin has proven more effective at preventing life-threatening clots in people who suffer strokes than the older version of the drug, a new study finds.

The incidence of clots in the lungs and legs of stroke patients who got the engineered form, called enoxaparin, was 43 percent lower than in those who got ordinary heparin, researchers said.

"This is the first big trial in which the two treatments have gone head to head," said lead researcher Dr. David G. Sherman, a professor of medicine and neurology at the University of Texas Health Science Center, in San Antonio. "Enoxaparin pretty convincingly appears to work better."

"Now that the results have been published, the question is, what will the bodies that write guidelines for management of stroke do?" Sherman added. "Because the results are so consistent, my guess is that the guidelines will say that stroke patients should be anticoagulated and that, because enoxaparin appears to be most efficient, it will become the standard."

The trial was funded by Sanofi Aventis, the maker of enoxaparin (Lovenox).

The finding, reported in the April 21 issue of The Lancet, is potentially applicable to more than 700,000 people who suffer strokes in the United States each year, Sherman said. These patients are at high risk of clotting because of their forced inactivity. In fact, the 1,762 stroke patients in the study received anticoagulant treatment only if they were unable to walk.

Half of the patients were given one injection of enoxaparin a day, the other half received two daily injections of heparin. They were then studied for the presence of blood clots in the legs and lungs.

The study included only patients who suffered ischemic stroke, the most common kind. In this type of attack a blood clot blocks a brain artery. However, Sherman said there are indications that the results also apply to people who have hemorrhagic strokes, in which a blood vessel bursts.

Cost remains a potential issue, however, because enoxaparin is much more expensive than ordinary heparin. Sherman's group is working on an analysis determining the economic impact of a shift to using enoxaparin on the total cost of treating stroke.

One prior study has indicated that introducing the drug might actually lead to cost reductions, said Dr. Richard M. Weinberg, chief quality officer of the Stamford Health System in Connecticut. His team tracked costs across 33 hospitals.

"On average, there is a big cost difference between the two: $1-a-day for heparin, $25 a day for Lovenox," he said. However, "over six years, when we looked at all the adult discharges and made adjustments for [illness] severity and risk, overall it was cheaper to treat with Lovenox."

There are several possible explanations for the lower overall cost, Weinberg said. "Most patients getting Lovenox can be managed without the frequent tests needed for heparin," he said. "In addition to reduced laboratory testing, a reduction in the length of stay and less time spent in the ICU [intensive care unit] are possible explanations."